<!-- This button triggers the overlay and is it's origin -->
<button (click)="isOpen = !isOpen" type="button" cdkOverlayOrigin #trigger="cdkOverlayOrigin">
  {{isOpen ? "Close" : "Open"}}
</button>

<!-- This template displays the overlay content and is connected to the button -->
<ng-template
  cdkConnectedOverlay
  [cdkConnectedOverlayOrigin]="trigger"
  [cdkConnectedOverlayOpen]="isOpen"
>
  <ul class="example-list">
    <li>Item 1</li>
    <li>Item 2</li>
    <li>Item 3</li>
  </ul>
</ng-template>
